Data Cleaning & Manipulation

Monday, April 15

Today we will…

Comments from Week 2
New Material
- Introduce the dplyr package.
- Use dplyr verbs to manipulate data.
PA 3: Identify the Mystery College

Comments from Week 2

Read through your .html to make sure it looks correct.
- Is any of your code producing errors/warnings/messages?
- Are images appearing properly?
- Are hyperlinks working properly?
Do not install packages in Quarto code chunks!
- Remember: we only install packages once.
Make sure you cite external sources.
- E.g., many people used sapply() to get the variable data types – this is fine, but where did you find this solution?

Citing Your Sources

When you write code, you will need to reference function/package documentation and external resources.

This is part of being a programmer!

When you rely on external resources for an assignment in this course, you must cite your sources.

If you use any resources outside of the course text, the course slides, and the posted cheatsheets, you must include a citation!
You will lose points if you do not.

Example Data set – Cereal

library(liver)
data(cereal)

Data Structure
Head of the Data
Data Summary

str(cereal, give.attr = FALSE)

'data.frame':   77 obs. of  16 variables:
 $ name    : Factor w/ 77 levels "100% Bran","100% Natural Bran",..: 1 2 3 4 5 6 7 8 9 10 ...
 $ manuf   : Factor w/ 7 levels "A","G","K","N",..: 4 6 3 3 7 2 3 2 7 5 ...
 $ type    : Factor w/ 2 levels "cold","hot": 1 1 1 1 1 1 1 1 1 1 ...
 $ calories: int  70 120 70 50 110 110 110 130 90 90 ...
 $ protein : int  4 3 4 4 2 2 2 3 2 3 ...
 $ fat     : int  1 5 1 0 2 2 0 2 1 0 ...
 $ sodium  : int  130 15 260 140 200 180 125 210 200 210 ...
 $ fiber   : num  10 2 9 14 1 1.5 1 2 4 5 ...
 $ carbo   : num  5 8 7 8 14 10.5 11 18 15 13 ...
 $ sugars  : int  6 8 5 0 8 10 14 8 6 5 ...
 $ potass  : int  280 135 320 330 -1 70 30 100 125 190 ...
 $ vitamins: int  25 0 25 25 25 25 25 25 25 25 ...
 $ shelf   : int  3 3 3 3 3 1 2 3 1 3 ...
 $ weight  : num  1 1 1 1 1 1 1 1.33 1 1 ...
 $ cups    : num  0.33 1 0.33 0.5 0.75 0.75 1 0.75 0.67 0.67 ...
 $ rating  : num  68.4 34 59.4 93.7 34.4 ...

head(cereal)

                       name manuf type calories protein fat sodium fiber carbo
1                 100% Bran     N cold       70       4   1    130  10.0   5.0
2         100% Natural Bran     Q cold      120       3   5     15   2.0   8.0
3                  All-Bran     K cold       70       4   1    260   9.0   7.0
4 All-Bran with Extra Fiber     K cold       50       4   0    140  14.0   8.0
5            Almond Delight     R cold      110       2   2    200   1.0  14.0
6   Apple Cinnamon Cheerios     G cold      110       2   2    180   1.5  10.5
  sugars potass vitamins shelf weight cups   rating
1      6    280       25     3      1 0.33 68.40297
2      8    135        0     3      1 1.00 33.98368
3      5    320       25     3      1 0.33 59.42551
4      0    330       25     3      1 0.50 93.70491
5      8     -1       25     3      1 0.75 34.38484
6     10     70       25     1      1 0.75 29.50954

summary(cereal)

                        name    manuf    type       calories    
 100% Bran                : 1   A: 1   cold:74   Min.   : 50.0  
 100% Natural Bran        : 1   G:22   hot : 3   1st Qu.:100.0  
 All-Bran                 : 1   K:23             Median :110.0  
 All-Bran with Extra Fiber: 1   N: 6             Mean   :106.9  
 Almond Delight           : 1   P: 9             3rd Qu.:110.0  
 Apple Cinnamon Cheerios  : 1   Q: 8             Max.   :160.0  
 (Other)                  :71   R: 8                            
    protein           fat            sodium          fiber       
 Min.   :1.000   Min.   :0.000   Min.   :  0.0   Min.   : 0.000  
 1st Qu.:2.000   1st Qu.:0.000   1st Qu.:130.0   1st Qu.: 1.000  
 Median :3.000   Median :1.000   Median :180.0   Median : 2.000  
 Mean   :2.545   Mean   :1.013   Mean   :159.7   Mean   : 2.152  
 3rd Qu.:3.000   3rd Qu.:2.000   3rd Qu.:210.0   3rd Qu.: 3.000  
 Max.   :6.000   Max.   :5.000   Max.   :320.0   Max.   :14.000  
                                                                 
     carbo          sugars           potass          vitamins     
 Min.   :-1.0   Min.   :-1.000   Min.   : -1.00   Min.   :  0.00  
 1st Qu.:12.0   1st Qu.: 3.000   1st Qu.: 40.00   1st Qu.: 25.00  
 Median :14.0   Median : 7.000   Median : 90.00   Median : 25.00  
 Mean   :14.6   Mean   : 6.922   Mean   : 96.08   Mean   : 28.25  
 3rd Qu.:17.0   3rd Qu.:11.000   3rd Qu.:120.00   3rd Qu.: 25.00  
 Max.   :23.0   Max.   :15.000   Max.   :330.00   Max.   :100.00  
                                                                  
     shelf           weight          cups           rating     
 Min.   :1.000   Min.   :0.50   Min.   :0.250   Min.   :18.04  
 1st Qu.:1.000   1st Qu.:1.00   1st Qu.:0.670   1st Qu.:33.17  
 Median :2.000   Median :1.00   Median :0.750   Median :40.40  
 Mean   :2.208   Mean   :1.03   Mean   :0.821   Mean   :42.67  
 3rd Qu.:3.000   3rd Qu.:1.00   3rd Qu.:1.000   3rd Qu.:50.83  
 Max.   :3.000   Max.   :1.50   Max.   :1.500   Max.   :93.70

Data Wrangling with `dplyr`

(Allison Horst)

`dplyr`

dplyr is part of the tidyverse that provides us with the Grammar of Data Manipulation.

This package gives us the tools to wrangle, manipulate, and tidy our data with ease.
Check out the dplyr cheatsheet.

`dplyr` verbs

filter() – select rows based on their values
arrange() – sort rows based on their values
select() – select columns
mutate() – add new columns by transforming other columns
summarize() – perform summary operations on columns
group_by() – facilitate group-wise operations

Use the pipe operator (|> or %>%) to chain together data wrangling operations.

The Pipe Operator

No matter how complex and polished the individual operations are, it is often the quality of the glue that most directly determines the power of the system.

— Hal Abelson

The Pipe Operator

With dplyr, your code should read like a sentence.
The data is the primary object in your sentence, so it should come first in your code.

The pipe operator is an important part of that readability.

The Pipe Operator

The pipe specifies a sequence of operations.
The output from one operation is passed into the first argument of the next operation.

The “original” pipe: %>%
- Loaded with tidyverse package (part of magrittr).
The “native” pipe: |>
- Created in R version 4.1.0.
- Tools > Global Options... > Code > check Use native pipe operator box.

The Pipe Operator

dr_rehnberg |>
  play_a_sport()

dr_rehnberg |>
  put_on("cleats") |>
  play_a_sport(type = "soccer")

Data Comes First!

filter(.data = cereal, ...)
select(.data = cereal, ...)
mutate(.data = cereal, ...)

These are equivalent:

summary(.data = cereal)

cereal |> 
  summary()

The pipe operator is your friend!

You can also pipe manipulated data or summaries directly into your ggplot2 code for plotting.

`filter()`

(Allison Horst)

`filter()`

We filter to the rows (observations) we would like to keep in the data.

cereal |> 
  filter(sugars < 5)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8	0	330	25	3	1.00	0.50	93.70491
Cheerios	G	cold	110	6	2	290	2.0	17	1	105	25	1	1.00	1.25	50.76500
Corn Chex	R	cold	110	2	0	280	0.0	22	3	25	25	1	1.00	1.00	41.44502
Corn Flakes	K	cold	100	2	0	290	1.0	21	2	35	25	1	1.00	1.00	45.86332
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21	0	-1	0	2	1.00	1.00	64.53382
Crispix	K	cold	110	2	0	220	1.0	21	3	30	25	3	1.00	1.00	46.89564
Grape-Nuts	P	cold	110	3	0	170	3.0	17	3	90	25	3	1.00	0.25	53.37101
Great Grains Pecan	P	cold	120	3	3	75	3.0	13	4	100	25	3	1.00	0.33	45.81172
Kix	G	cold	110	2	1	260	0.0	21	3	40	25	2	1.00	1.50	39.24111
Maypo	A	hot	100	4	1	0	0.0	16	3	95	25	2	1.00	1.00	54.85092
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18	2	90	25	3	1.00	1.00	59.64284
Product 19	K	cold	100	3	0	320	1.0	20	3	45	100	3	1.00	1.00	41.50354
Puffed Rice	Q	cold	50	1	0	0	0.0	13	0	15	0	3	0.50	1.00	60.75611
Puffed Wheat	Q	cold	50	2	0	0	1.0	10	0	50	0	3	0.50	1.00	63.00565
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1	-1	110	0	1	1.00	0.67	50.82839
Rice Chex	R	cold	110	1	0	240	0.0	23	2	30	25	1	1.00	1.13	41.99893
Rice Krispies	K	cold	110	2	0	290	0.0	22	3	35	25	1	1.00	1.00	40.56016
Shredded Wheat	N	cold	80	2	0	0	3.0	16	0	95	0	1	0.83	1.00	68.23588
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19	0	140	0	1	1.00	0.67	74.47295
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20	0	120	0	1	1.00	0.67	72.80179
Special K	K	cold	110	6	0	230	1.0	16	3	55	25	1	1.00	1.00	53.13132
Total Corn Flakes	G	cold	110	2	1	200	0.0	21	3	35	100	3	1.00	1.00	38.83975
Total Whole Grain	G	cold	100	3	1	200	3.0	16	3	110	100	3	1.00	1.00	46.65884
Triples	G	cold	110	2	1	250	0.0	21	3	60	25	3	1.00	0.75	39.10617
Wheat Chex	R	cold	100	3	1	230	3.0	17	3	115	25	1	1.00	0.67	49.78744
Wheaties	G	cold	100	3	1	200	3.0	17	3	110	25	1	1.00	1.00	51.59219

`filter()`

We can add multiple filters to our data, to get a more specific subset.

cereal |> 
  filter(sugars < 5,
         type == "hot")

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21	0	-1	0	2	1	1.00	64.53382
Maypo	A	hot	100	4	1	0	0.0	16	3	95	25	2	1	1.00	54.85092
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1	-1	110	0	1	1	0.67	50.82839

`filter()`: Handy Helpers!

> – greater than
< – less than
== – equal to
! – not
%in% – checks if an element belongs to a vector
is.na() – binary evaluation of missing values

& and , – and
| – or

`filter()`: `|`

cereal |> 
  filter(sugars < 5,
         type == "hot")

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21	0	-1	0	2	1	1.00	64.53382
Maypo	A	hot	100	4	1	0	0.0	16	3	95	25	2	1	1.00	54.85092
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1	-1	110	0	1	1	0.67	50.82839

What if I wanted either non-sugary cereals or hot cereals…

Code

cereal |> 
  filter(sugars < 5 |
           type == "hot")

`filter()`: `%in%`

Are you interested in observations with values in a list of levels?

cereal |> 
  filter(name %in% c("Cheerios", "Cinnamon Toast Crunch", "Raisin Bran", "Cracklin' Oat Bran"))

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Cheerios	G	cold	110	6	2	290	2	17	1	105	25	1	1.00	1.25	50.76500
Cinnamon Toast Crunch	G	cold	120	1	3	210	0	13	9	45	25	2	1.00	0.75	19.82357
Cracklin' Oat Bran	K	cold	110	3	3	140	4	10	7	160	25	3	1.00	0.50	40.44877
Raisin Bran	K	cold	120	3	1	210	5	14	12	240	25	2	1.33	0.75	39.25920

How do we “filter” in base `R`?

You can use the subset() function!

cereal |> 
  subset(name %in% c("Cheerios", "Cinnamon Toast Crunch", "Raisin Bran", "Cracklin' Oat Bran"))

	name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
12	Cheerios	G	cold	110	6	2	290	2	17	1	105	25	1	1.00	1.25	50.76500
13	Cinnamon Toast Crunch	G	cold	120	1	3	210	0	13	9	45	25	2	1.00	0.75	19.82357
20	Cracklin' Oat Bran	K	cold	110	3	3	140	4	10	7	160	25	3	1.00	0.50	40.44877
59	Raisin Bran	K	cold	120	3	1	210	5	14	12	240	25	2	1.33	0.75	39.25920

cereal |> 
  subset(sugars < 5 & type == "hot")

	name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
21	Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21	0	-1	0	2	1	1.00	64.53382
44	Maypo	A	hot	100	4	1	0	0.0	16	3	95	25	2	1	1.00	54.85092
58	Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1	-1	110	0	1	1	0.67	50.82839

`arrange()`

We arrange the rows of the data in order of a particular variable.

cereal |> 
  arrange(sodium)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514
Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092
Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611
Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839
Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314
Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368
Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399
Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244
Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005
Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382
Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279
Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686
Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409
Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297
Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576
Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491
Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021
Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877
Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620
Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690
Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340
Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330
Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807
Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976
Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705
Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101
Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368
Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284
Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954
Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645
Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651
Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241
Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451
Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086
Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429
Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484
Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025
Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059
Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975
Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884
Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219
Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756
Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856
Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381
Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357
Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920
Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285
Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564
Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129
Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596
Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232
Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132
Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744
Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549
Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893
Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222
Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551
Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111
Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502
Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404
Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500
Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332
Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016
Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354

`arrange()`

We can arrange by multiple variables.

cereal |> 
  arrange(sodium, sugars) |>
  select(c(1:3,7, 10))

name	manuf	type	sodium	sugars
Quaker Oatmeal	Q	hot	0	-1
Puffed Rice	Q	cold	0	0
Puffed Wheat	Q	cold	0	0
Shredded Wheat	N	cold	0	0
Shredded Wheat 'n'Bran	N	cold	0	0
Shredded Wheat spoon size	N	cold	0	0
Maypo	A	hot	0	3
Raisin Squares	K	cold	0	6
Frosted Mini-Wheats	K	cold	0	7
Strawberry Fruit Wheats	N	cold	15	5
100% Natural Bran	Q	cold	15	8
Golden Crisp	P	cold	45	15
Smacks	K	cold	70	15
Great Grains Pecan	P	cold	75	4
Cream of Wheat (Quick)	N	hot	80	0
Corn Pops	K	cold	90	12
Muesli Raisins; Dates; & Almonds	R	cold	95	11
Froot Loops	K	cold	125	13
Apple Jacks	K	cold	125	14
100% Bran	N	cold	130	6
Quaker Oat Squares	Q	cold	135	6
Fruity Pebbles	P	cold	135	12
All-Bran with Extra Fiber	K	cold	140	0
Grape Nuts Flakes	P	cold	140	5
Clusters	G	cold	140	7
Cracklin' Oat Bran	K	cold	140	7
Raisin Nut Bran	G	cold	140	8
Crispy Wheat & Raisins	G	cold	140	10
Trix	G	cold	140	12
Life	Q	cold	150	6
Muesli Raisins; Peaches; & Pecans	R	cold	150	11
Mueslix Crispy Blend	K	cold	150	13
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	160	10
Nutri-grain Wheat	K	cold	170	2
Grape-Nuts	P	cold	170	3
Just Right Crunchy Nuggets	K	cold	170	6
Just Right Fruit & Nut	K	cold	170	9
Oatmeal Raisin Crisp	G	cold	170	10
Apple Cinnamon Cheerios	G	cold	180	10
Honey-comb	P	cold	180	11
Lucky Charms	G	cold	180	12
Cocoa Puffs	G	cold	180	13
Count Chocula	G	cold	180	13
Double Chex	R	cold	190	5
Nut&Honey Crunch	K	cold	190	9
Total Raisin Bran	G	cold	190	14
Total Corn Flakes	G	cold	200	3
Total Whole Grain	G	cold	200	3
Wheaties	G	cold	200	3
Bran Chex	R	cold	200	6
Almond Delight	R	cold	200	8
Wheaties Honey Gold	G	cold	200	8
Frosted Flakes	K	cold	200	11
Post Nat. Raisin Bran	P	cold	200	14
Bran Flakes	P	cold	210	5
Basic 4	G	cold	210	8
Cinnamon Toast Crunch	G	cold	210	9
Raisin Bran	K	cold	210	12
Crispix	K	cold	220	3
Multi-Grain Cheerios	G	cold	220	6
Nutri-Grain Almond-Raisin	K	cold	220	7
Honey Graham Ohs	Q	cold	220	11
Cap'n'Crunch	Q	cold	220	12
Special K	K	cold	230	3
Wheat Chex	R	cold	230	3
Rice Chex	R	cold	240	2
Fruitful Bran	K	cold	240	12
Triples	G	cold	250	3
Honey Nut Cheerios	G	cold	250	10
Kix	G	cold	260	3
All-Bran	K	cold	260	5
Corn Chex	R	cold	280	3
Golden Grahams	G	cold	280	9
Cheerios	G	cold	290	1
Corn Flakes	K	cold	290	2
Rice Krispies	K	cold	290	3
Product 19	K	cold	320	3

`arrange()`: Descending Order

Default is ascending order…

cereal |> 
  arrange(sodium)

…but can add desc() to get descending order!

cereal |> 
  arrange(desc(sodium))

`slice_max()`

Selects the n rows with the maximum values of the specified variable.

cereal |> 
  slice_max(order_by = sugars, n = 3)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Golden Crisp	P	cold	100	2	0	45	0	11	15	40	25	1	1.00	0.88	35.25244
Smacks	K	cold	110	2	1	70	1	9	15	40	25	2	1.00	0.75	31.23005
Apple Jacks	K	cold	110	2	0	125	1	11	14	30	25	2	1.00	1.00	33.17409
Post Nat. Raisin Bran	P	cold	120	3	1	200	6	11	14	260	25	3	1.33	0.67	37.84059
Total Raisin Bran	G	cold	140	3	1	190	4	15	14	230	100	3	1.50	1.00	28.59278

cereal |> 
  slice_max(order_by = sugars, n = 3, with_ties = FALSE)

How do we “arrange” in base `R`?

You can use the order() function!

cereal[order(cereal$sodium),]

	name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
27	Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514
44	Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092
55	Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611
56	Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565
58	Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839
61	Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314
64	Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588
65	Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295
66	Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179
2	100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368
69	Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399
31	Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244
67	Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005
35	Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172
21	Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382
18	Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279
45	Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686
7	Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409
25	Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758
1	100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297
30	Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576
57	Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187
4	All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491
14	Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021
20	Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877
23	Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620
33	Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690
60	Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340
74	Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330
42	Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807
46	Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976
47	Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335
28	Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705
34	Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101
39	Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368
40	Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151
51	Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284
52	Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084
6	Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954
15	Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645
19	Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651
38	Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241
43	Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451
24	Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086
49	Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429
71	Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278
5	Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484
9	Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025
26	Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597
53	Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059
70	Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975
72	Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884
76	Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219
77	Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756
8	Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856
10	Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381
13	Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357
59	Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920
11	Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285
22	Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564
36	Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129
48	Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596
50	Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232
68	Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132
75	Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744
29	Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549
62	Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893
37	Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222
73	Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617
3	All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551
41	Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111
16	Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502
32	Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404
12	Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500
17	Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332
63	Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016
54	Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354

cereal[order(cereal$sodium, cereal$sugars),]

	name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
58	Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839
55	Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611
56	Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565
64	Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588
65	Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295
66	Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179
44	Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092
61	Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314
27	Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514
69	Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399
2	100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368
31	Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244
67	Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005
35	Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172
21	Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382
18	Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279
45	Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686
25	Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758
7	Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409
1	100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297
57	Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187
30	Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576
4	All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491
33	Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690
14	Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021
20	Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877
60	Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340
23	Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620
74	Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330
42	Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807
46	Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976
47	Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335
28	Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705
51	Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284
34	Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101
39	Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368
40	Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151
52	Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084
6	Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954
38	Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241
43	Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451
15	Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645
19	Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651
24	Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086
49	Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429
71	Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278
70	Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975
72	Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884
76	Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219
9	Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025
5	Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484
77	Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756
26	Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597
53	Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059
10	Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381
8	Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856
13	Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357
59	Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920
22	Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564
48	Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596
50	Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232
36	Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129
11	Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285
68	Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132
75	Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744
62	Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893
29	Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549
73	Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617
37	Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222
41	Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111
3	All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551
16	Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502
32	Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404
12	Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500
17	Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332
63	Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016
54	Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354

`select()`

We select which variables we would like to remain in the data.

cereal |> 
  select(name, manuf, calories, cups)

name	manuf	calories	cups
100% Bran	N	70	0.33
100% Natural Bran	Q	120	1.00
All-Bran	K	70	0.33
All-Bran with Extra Fiber	K	50	0.50
Almond Delight	R	110	0.75
Apple Cinnamon Cheerios	G	110	0.75
Apple Jacks	K	110	1.00
Basic 4	G	130	0.75
Bran Chex	R	90	0.67
Bran Flakes	P	90	0.67
Cap'n'Crunch	Q	120	0.75
Cheerios	G	110	1.25
Cinnamon Toast Crunch	G	120	0.75
Clusters	G	110	0.50
Cocoa Puffs	G	110	1.00
Corn Chex	R	110	1.00
Corn Flakes	K	100	1.00
Corn Pops	K	110	1.00
Count Chocula	G	110	1.00
Cracklin' Oat Bran	K	110	0.50
Cream of Wheat (Quick)	N	100	1.00
Crispix	K	110	1.00
Crispy Wheat & Raisins	G	100	0.75
Double Chex	R	100	0.75
Froot Loops	K	110	1.00
Frosted Flakes	K	110	0.75
Frosted Mini-Wheats	K	100	0.80
Fruit & Fibre Dates; Walnuts; and Oats	P	120	0.67
Fruitful Bran	K	120	0.67
Fruity Pebbles	P	110	0.75
Golden Crisp	P	100	0.88
Golden Grahams	G	110	0.75
Grape Nuts Flakes	P	100	0.88
Grape-Nuts	P	110	0.25
Great Grains Pecan	P	120	0.33
Honey Graham Ohs	Q	120	1.00
Honey Nut Cheerios	G	110	0.75
Honey-comb	P	110	1.33
Just Right Crunchy Nuggets	K	110	1.00
Just Right Fruit & Nut	K	140	0.75
Kix	G	110	1.50
Life	Q	100	0.67
Lucky Charms	G	110	1.00
Maypo	A	100	1.00
Muesli Raisins; Dates; & Almonds	R	150	1.00
Muesli Raisins; Peaches; & Pecans	R	150	1.00
Mueslix Crispy Blend	K	160	0.67
Multi-Grain Cheerios	G	100	1.00
Nut&Honey Crunch	K	120	0.67
Nutri-Grain Almond-Raisin	K	140	0.67
Nutri-grain Wheat	K	90	1.00
Oatmeal Raisin Crisp	G	130	0.50
Post Nat. Raisin Bran	P	120	0.67
Product 19	K	100	1.00
Puffed Rice	Q	50	1.00
Puffed Wheat	Q	50	1.00
Quaker Oat Squares	Q	100	0.50
Quaker Oatmeal	Q	100	0.67
Raisin Bran	K	120	0.75
Raisin Nut Bran	G	100	0.50
Raisin Squares	K	90	0.50
Rice Chex	R	110	1.13
Rice Krispies	K	110	1.00
Shredded Wheat	N	80	1.00
Shredded Wheat 'n'Bran	N	90	0.67
Shredded Wheat spoon size	N	90	0.67
Smacks	K	110	0.75
Special K	K	110	1.00
Strawberry Fruit Wheats	N	90	1.00
Total Corn Flakes	G	110	1.00
Total Raisin Bran	G	140	1.00
Total Whole Grain	G	100	1.00
Triples	G	110	0.75
Trix	G	110	1.00
Wheat Chex	R	100	0.67
Wheaties	G	100	1.00
Wheaties Honey Gold	G	110	0.75

`select()`

You can use : to select a sequence of columns.

cereal |> 
  select(name:calories)

name	manuf	type	calories
100% Bran	N	cold	70
100% Natural Bran	Q	cold	120
All-Bran	K	cold	70
All-Bran with Extra Fiber	K	cold	50
Almond Delight	R	cold	110
Apple Cinnamon Cheerios	G	cold	110
Apple Jacks	K	cold	110
Basic 4	G	cold	130
Bran Chex	R	cold	90
Bran Flakes	P	cold	90
Cap'n'Crunch	Q	cold	120
Cheerios	G	cold	110
Cinnamon Toast Crunch	G	cold	120
Clusters	G	cold	110
Cocoa Puffs	G	cold	110
Corn Chex	R	cold	110
Corn Flakes	K	cold	100
Corn Pops	K	cold	110
Count Chocula	G	cold	110
Cracklin' Oat Bran	K	cold	110
Cream of Wheat (Quick)	N	hot	100
Crispix	K	cold	110
Crispy Wheat & Raisins	G	cold	100
Double Chex	R	cold	100
Froot Loops	K	cold	110
Frosted Flakes	K	cold	110
Frosted Mini-Wheats	K	cold	100
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120
Fruitful Bran	K	cold	120
Fruity Pebbles	P	cold	110
Golden Crisp	P	cold	100
Golden Grahams	G	cold	110
Grape Nuts Flakes	P	cold	100
Grape-Nuts	P	cold	110
Great Grains Pecan	P	cold	120
Honey Graham Ohs	Q	cold	120
Honey Nut Cheerios	G	cold	110
Honey-comb	P	cold	110
Just Right Crunchy Nuggets	K	cold	110
Just Right Fruit & Nut	K	cold	140
Kix	G	cold	110
Life	Q	cold	100
Lucky Charms	G	cold	110
Maypo	A	hot	100
Muesli Raisins; Dates; & Almonds	R	cold	150
Muesli Raisins; Peaches; & Pecans	R	cold	150
Mueslix Crispy Blend	K	cold	160
Multi-Grain Cheerios	G	cold	100
Nut&Honey Crunch	K	cold	120
Nutri-Grain Almond-Raisin	K	cold	140
Nutri-grain Wheat	K	cold	90
Oatmeal Raisin Crisp	G	cold	130
Post Nat. Raisin Bran	P	cold	120
Product 19	K	cold	100
Puffed Rice	Q	cold	50
Puffed Wheat	Q	cold	50
Quaker Oat Squares	Q	cold	100
Quaker Oatmeal	Q	hot	100
Raisin Bran	K	cold	120
Raisin Nut Bran	G	cold	100
Raisin Squares	K	cold	90
Rice Chex	R	cold	110
Rice Krispies	K	cold	110
Shredded Wheat	N	cold	80
Shredded Wheat 'n'Bran	N	cold	90
Shredded Wheat spoon size	N	cold	90
Smacks	K	cold	110
Special K	K	cold	110
Strawberry Fruit Wheats	N	cold	90
Total Corn Flakes	G	cold	110
Total Raisin Bran	G	cold	140
Total Whole Grain	G	cold	100
Triples	G	cold	110
Trix	G	cold	110
Wheat Chex	R	cold	100
Wheaties	G	cold	100
Wheaties Honey Gold	G	cold	110

You can remove columns from the dataset using a -.

cereal |> 
  select(-rating)

`select()`: Reordering

You can reorder columns inside of select().

cereal |> 
  select(name, rating, manuf, type, calories, cups, weight,
         everything())

name	rating	manuf	type	calories	cups	weight	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf
100% Bran	68.40297	N	cold	70	0.33	1.00	4	1	130	10.0	5.0	6	280	25	3
100% Natural Bran	33.98368	Q	cold	120	1.00	1.00	3	5	15	2.0	8.0	8	135	0	3
All-Bran	59.42551	K	cold	70	0.33	1.00	4	1	260	9.0	7.0	5	320	25	3
All-Bran with Extra Fiber	93.70491	K	cold	50	0.50	1.00	4	0	140	14.0	8.0	0	330	25	3
Almond Delight	34.38484	R	cold	110	0.75	1.00	2	2	200	1.0	14.0	8	-1	25	3
Apple Cinnamon Cheerios	29.50954	G	cold	110	0.75	1.00	2	2	180	1.5	10.5	10	70	25	1
Apple Jacks	33.17409	K	cold	110	1.00	1.00	2	0	125	1.0	11.0	14	30	25	2
Basic 4	37.03856	G	cold	130	0.75	1.33	3	2	210	2.0	18.0	8	100	25	3
Bran Chex	49.12025	R	cold	90	0.67	1.00	2	1	200	4.0	15.0	6	125	25	1
Bran Flakes	53.31381	P	cold	90	0.67	1.00	3	0	210	5.0	13.0	5	190	25	3
Cap'n'Crunch	18.04285	Q	cold	120	0.75	1.00	1	2	220	0.0	12.0	12	35	25	2
Cheerios	50.76500	G	cold	110	1.25	1.00	6	2	290	2.0	17.0	1	105	25	1
Cinnamon Toast Crunch	19.82357	G	cold	120	0.75	1.00	1	3	210	0.0	13.0	9	45	25	2
Clusters	40.40021	G	cold	110	0.50	1.00	3	2	140	2.0	13.0	7	105	25	3
Cocoa Puffs	22.73645	G	cold	110	1.00	1.00	1	1	180	0.0	12.0	13	55	25	2
Corn Chex	41.44502	R	cold	110	1.00	1.00	2	0	280	0.0	22.0	3	25	25	1
Corn Flakes	45.86332	K	cold	100	1.00	1.00	2	0	290	1.0	21.0	2	35	25	1
Corn Pops	35.78279	K	cold	110	1.00	1.00	1	0	90	1.0	13.0	12	20	25	2
Count Chocula	22.39651	G	cold	110	1.00	1.00	1	1	180	0.0	12.0	13	65	25	2
Cracklin' Oat Bran	40.44877	K	cold	110	0.50	1.00	3	3	140	4.0	10.0	7	160	25	3
Cream of Wheat (Quick)	64.53382	N	hot	100	1.00	1.00	3	0	80	1.0	21.0	0	-1	0	2
Crispix	46.89564	K	cold	110	1.00	1.00	2	0	220	1.0	21.0	3	30	25	3
Crispy Wheat & Raisins	36.17620	G	cold	100	0.75	1.00	2	1	140	2.0	11.0	10	120	25	3
Double Chex	44.33086	R	cold	100	0.75	1.00	2	0	190	1.0	18.0	5	80	25	3
Froot Loops	32.20758	K	cold	110	1.00	1.00	2	1	125	1.0	11.0	13	30	25	2
Frosted Flakes	31.43597	K	cold	110	0.75	1.00	1	0	200	1.0	14.0	11	25	25	1
Frosted Mini-Wheats	58.34514	K	cold	100	0.80	1.00	3	0	0	3.0	14.0	7	100	25	2
Fruit & Fibre Dates; Walnuts; and Oats	40.91705	P	cold	120	0.67	1.25	3	2	160	5.0	12.0	10	200	25	3
Fruitful Bran	41.01549	K	cold	120	0.67	1.33	3	0	240	5.0	14.0	12	190	25	3
Fruity Pebbles	28.02576	P	cold	110	0.75	1.00	1	1	135	0.0	13.0	12	25	25	2
Golden Crisp	35.25244	P	cold	100	0.88	1.00	2	0	45	0.0	11.0	15	40	25	1
Golden Grahams	23.80404	G	cold	110	0.75	1.00	1	1	280	0.0	15.0	9	45	25	2
Grape Nuts Flakes	52.07690	P	cold	100	0.88	1.00	3	1	140	3.0	15.0	5	85	25	3
Grape-Nuts	53.37101	P	cold	110	0.25	1.00	3	0	170	3.0	17.0	3	90	25	3
Great Grains Pecan	45.81172	P	cold	120	0.33	1.00	3	3	75	3.0	13.0	4	100	25	3
Honey Graham Ohs	21.87129	Q	cold	120	1.00	1.00	1	2	220	1.0	12.0	11	45	25	2
Honey Nut Cheerios	31.07222	G	cold	110	0.75	1.00	3	1	250	1.5	11.5	10	90	25	1
Honey-comb	28.74241	P	cold	110	1.33	1.00	1	0	180	0.0	14.0	11	35	25	1
Just Right Crunchy Nuggets	36.52368	K	cold	110	1.00	1.00	2	1	170	1.0	17.0	6	60	100	3
Just Right Fruit & Nut	36.47151	K	cold	140	0.75	1.30	3	1	170	2.0	20.0	9	95	100	3
Kix	39.24111	G	cold	110	1.50	1.00	2	1	260	0.0	21.0	3	40	25	2
Life	45.32807	Q	cold	100	0.67	1.00	4	2	150	2.0	12.0	6	95	25	2
Lucky Charms	26.73451	G	cold	110	1.00	1.00	2	1	180	0.0	12.0	12	55	25	2
Maypo	54.85092	A	hot	100	1.00	1.00	4	1	0	0.0	16.0	3	95	25	2
Muesli Raisins; Dates; & Almonds	37.13686	R	cold	150	1.00	1.00	4	3	95	3.0	16.0	11	170	25	3
Muesli Raisins; Peaches; & Pecans	34.13976	R	cold	150	1.00	1.00	4	3	150	3.0	16.0	11	170	25	3
Mueslix Crispy Blend	30.31335	K	cold	160	0.67	1.50	3	2	150	3.0	17.0	13	160	25	3
Multi-Grain Cheerios	40.10596	G	cold	100	1.00	1.00	2	1	220	2.0	15.0	6	90	25	1
Nut&Honey Crunch	29.92429	K	cold	120	0.67	1.00	2	1	190	0.0	15.0	9	40	25	2
Nutri-Grain Almond-Raisin	40.69232	K	cold	140	0.67	1.33	3	2	220	3.0	21.0	7	130	25	3
Nutri-grain Wheat	59.64284	K	cold	90	1.00	1.00	3	0	170	3.0	18.0	2	90	25	3
Oatmeal Raisin Crisp	30.45084	G	cold	130	0.50	1.25	3	2	170	1.5	13.5	10	120	25	3
Post Nat. Raisin Bran	37.84059	P	cold	120	0.67	1.33	3	1	200	6.0	11.0	14	260	25	3
Product 19	41.50354	K	cold	100	1.00	1.00	3	0	320	1.0	20.0	3	45	100	3
Puffed Rice	60.75611	Q	cold	50	1.00	0.50	1	0	0	0.0	13.0	0	15	0	3
Puffed Wheat	63.00565	Q	cold	50	1.00	0.50	2	0	0	1.0	10.0	0	50	0	3
Quaker Oat Squares	49.51187	Q	cold	100	0.50	1.00	4	1	135	2.0	14.0	6	110	25	3
Quaker Oatmeal	50.82839	Q	hot	100	0.67	1.00	5	2	0	2.7	-1.0	-1	110	0	1
Raisin Bran	39.25920	K	cold	120	0.75	1.33	3	1	210	5.0	14.0	12	240	25	2
Raisin Nut Bran	39.70340	G	cold	100	0.50	1.00	3	2	140	2.5	10.5	8	140	25	3
Raisin Squares	55.33314	K	cold	90	0.50	1.00	2	0	0	2.0	15.0	6	110	25	3
Rice Chex	41.99893	R	cold	110	1.13	1.00	1	0	240	0.0	23.0	2	30	25	1
Rice Krispies	40.56016	K	cold	110	1.00	1.00	2	0	290	0.0	22.0	3	35	25	1
Shredded Wheat	68.23588	N	cold	80	1.00	0.83	2	0	0	3.0	16.0	0	95	0	1
Shredded Wheat 'n'Bran	74.47295	N	cold	90	0.67	1.00	3	0	0	4.0	19.0	0	140	0	1
Shredded Wheat spoon size	72.80179	N	cold	90	0.67	1.00	3	0	0	3.0	20.0	0	120	0	1
Smacks	31.23005	K	cold	110	0.75	1.00	2	1	70	1.0	9.0	15	40	25	2
Special K	53.13132	K	cold	110	1.00	1.00	6	0	230	1.0	16.0	3	55	25	1
Strawberry Fruit Wheats	59.36399	N	cold	90	1.00	1.00	2	0	15	3.0	15.0	5	90	25	2
Total Corn Flakes	38.83975	G	cold	110	1.00	1.00	2	1	200	0.0	21.0	3	35	100	3
Total Raisin Bran	28.59278	G	cold	140	1.00	1.50	3	1	190	4.0	15.0	14	230	100	3
Total Whole Grain	46.65884	G	cold	100	1.00	1.00	3	1	200	3.0	16.0	3	110	100	3
Triples	39.10617	G	cold	110	0.75	1.00	2	1	250	0.0	21.0	3	60	25	3
Trix	27.75330	G	cold	110	1.00	1.00	1	1	140	0.0	13.0	12	25	25	2
Wheat Chex	49.78744	R	cold	100	0.67	1.00	3	1	230	3.0	17.0	3	115	25	1
Wheaties	51.59219	G	cold	100	1.00	1.00	3	1	200	3.0	17.0	3	110	25	1
Wheaties Honey Gold	36.18756	G	cold	110	0.75	1.00	2	1	200	1.0	16.0	8	60	25	1

`select()`: Handy Helpers!

everything() – selects all columns that you have not already specified
starts_with() – selects columns with names that start with the specified string
ends_with() – selects columns with names that end with the specified string
contains() – selects columns with names that contain the specified string

`rename()`

You can rename columns with select(), but all columns not specified will be dropped.
- Using the rename() function is easier!

cereal |> 
  rename(temp = type)

name	manuf	temp	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954
Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409
Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856
Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025
Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381
Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285
Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500
Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357
Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021
Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645
Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502
Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332
Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279
Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651
Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382
Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564
Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620
Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086
Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758
Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597
Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705
Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549
Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576
Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244
Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404
Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690
Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101
Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172
Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129
Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222
Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241
Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368
Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151
Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111
Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807
Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451
Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092
Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686
Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976
Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335
Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596
Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429
Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284
Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059
Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354
Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611
Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565
Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839
Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920
Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340
Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314
Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893
Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016
Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179
Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005
Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132
Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399
Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975
Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278
Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884
Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617
Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330
Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744
Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219
Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756

How do we “select” in base `R`?

You don’t really use a specific function!

cereal[,c("name", "manuf", "calories", "cups")]

name	manuf	calories	cups
100% Bran	N	70	0.33
100% Natural Bran	Q	120	1.00
All-Bran	K	70	0.33
All-Bran with Extra Fiber	K	50	0.50
Almond Delight	R	110	0.75
Apple Cinnamon Cheerios	G	110	0.75
Apple Jacks	K	110	1.00
Basic 4	G	130	0.75
Bran Chex	R	90	0.67
Bran Flakes	P	90	0.67
Cap'n'Crunch	Q	120	0.75
Cheerios	G	110	1.25
Cinnamon Toast Crunch	G	120	0.75
Clusters	G	110	0.50
Cocoa Puffs	G	110	1.00
Corn Chex	R	110	1.00
Corn Flakes	K	100	1.00
Corn Pops	K	110	1.00
Count Chocula	G	110	1.00
Cracklin' Oat Bran	K	110	0.50
Cream of Wheat (Quick)	N	100	1.00
Crispix	K	110	1.00
Crispy Wheat & Raisins	G	100	0.75
Double Chex	R	100	0.75
Froot Loops	K	110	1.00
Frosted Flakes	K	110	0.75
Frosted Mini-Wheats	K	100	0.80
Fruit & Fibre Dates; Walnuts; and Oats	P	120	0.67
Fruitful Bran	K	120	0.67
Fruity Pebbles	P	110	0.75
Golden Crisp	P	100	0.88
Golden Grahams	G	110	0.75
Grape Nuts Flakes	P	100	0.88
Grape-Nuts	P	110	0.25
Great Grains Pecan	P	120	0.33
Honey Graham Ohs	Q	120	1.00
Honey Nut Cheerios	G	110	0.75
Honey-comb	P	110	1.33
Just Right Crunchy Nuggets	K	110	1.00
Just Right Fruit & Nut	K	140	0.75
Kix	G	110	1.50
Life	Q	100	0.67
Lucky Charms	G	110	1.00
Maypo	A	100	1.00
Muesli Raisins; Dates; & Almonds	R	150	1.00
Muesli Raisins; Peaches; & Pecans	R	150	1.00
Mueslix Crispy Blend	K	160	0.67
Multi-Grain Cheerios	G	100	1.00
Nut&Honey Crunch	K	120	0.67
Nutri-Grain Almond-Raisin	K	140	0.67
Nutri-grain Wheat	K	90	1.00
Oatmeal Raisin Crisp	G	130	0.50
Post Nat. Raisin Bran	P	120	0.67
Product 19	K	100	1.00
Puffed Rice	Q	50	1.00
Puffed Wheat	Q	50	1.00
Quaker Oat Squares	Q	100	0.50
Quaker Oatmeal	Q	100	0.67
Raisin Bran	K	120	0.75
Raisin Nut Bran	G	100	0.50
Raisin Squares	K	90	0.50
Rice Chex	R	110	1.13
Rice Krispies	K	110	1.00
Shredded Wheat	N	80	1.00
Shredded Wheat 'n'Bran	N	90	0.67
Shredded Wheat spoon size	N	90	0.67
Smacks	K	110	0.75
Special K	K	110	1.00
Strawberry Fruit Wheats	N	90	1.00
Total Corn Flakes	G	110	1.00
Total Raisin Bran	G	140	1.00
Total Whole Grain	G	100	1.00
Triples	G	110	0.75
Trix	G	110	1.00
Wheat Chex	R	100	0.67
Wheaties	G	100	1.00
Wheaties Honey Gold	G	110	0.75

cereal |> 
  subset(select = -c(rating))

colnames(cereal)[2:4] <- c("maker","temp","cals")

`mutate()`

(Allison Horst)

`mutate()`

The dataset gets mutated to either include a new variable…

cereal |> 
  mutate(potass_per_cup = potass / cups)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating	potass_per_cup
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297	848.484848
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368	135.000000
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551	969.696970
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491	660.000000
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484	-1.333333
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954	93.333333
Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409	30.000000
Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856	133.333333
Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025	186.567164
Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381	283.582090
Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285	46.666667
Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500	84.000000
Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357	60.000000
Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021	210.000000
Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645	55.000000
Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502	25.000000
Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332	35.000000
Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279	20.000000
Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651	65.000000
Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877	320.000000
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382	-1.000000
Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564	30.000000
Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620	160.000000
Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086	106.666667
Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758	30.000000
Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597	33.333333
Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514	125.000000
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705	298.507463
Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549	283.582090
Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576	33.333333
Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244	45.454546
Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404	60.000000
Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690	96.590909
Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101	360.000000
Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172	303.030303
Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129	45.000000
Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222	120.000000
Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241	26.315790
Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368	60.000000
Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151	126.666667
Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111	26.666667
Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807	141.791045
Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451	55.000000
Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092	95.000000
Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686	170.000000
Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976	170.000000
Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335	238.805970
Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596	90.000000
Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429	59.701493
Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232	194.029851
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284	90.000000
Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084	240.000000
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059	388.059702
Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354	45.000000
Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611	15.000000
Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565	50.000000
Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187	220.000000
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839	164.179104
Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920	320.000000
Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340	280.000000
Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314	220.000000
Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893	26.548673
Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016	35.000000
Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588	95.000000
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295	208.955224
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179	179.104478
Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005	53.333333
Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132	55.000000
Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399	90.000000
Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975	35.000000
Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278	230.000000
Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884	110.000000
Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617	80.000000
Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330	25.000000
Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744	171.641791
Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219	110.000000
Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756	80.000000

…OR revise an existing variable.

cereal |> 
  mutate(shelf = as.factor(shelf))

`mutate()`: Handy Helpers!

if_else() or case_when() – shortcut for if-else loop
as.factor(), as.numeric(), etc. – change variable type
+, -, *, / – basic mathematical operations
%% – modulo (returns the remainder when doing division)

How do we “mutate” in base `R`?

You can define new columns…

cereal$potass_per_cup <- cereal$potass / cereal$cups

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating	potass_per_cup
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297	848.484848
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368	135.000000
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551	969.696970
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491	660.000000
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484	-1.333333
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954	93.333333
Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409	30.000000
Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856	133.333333
Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025	186.567164
Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381	283.582090
Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285	46.666667
Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500	84.000000
Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357	60.000000
Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021	210.000000
Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645	55.000000
Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502	25.000000
Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332	35.000000
Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279	20.000000
Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651	65.000000
Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877	320.000000
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382	-1.000000
Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564	30.000000
Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620	160.000000
Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086	106.666667
Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758	30.000000
Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597	33.333333
Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514	125.000000
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705	298.507463
Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549	283.582090
Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576	33.333333
Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244	45.454546
Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404	60.000000
Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690	96.590909
Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101	360.000000
Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172	303.030303
Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129	45.000000
Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222	120.000000
Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241	26.315790
Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368	60.000000
Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151	126.666667
Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111	26.666667
Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807	141.791045
Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451	55.000000
Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092	95.000000
Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686	170.000000
Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976	170.000000
Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335	238.805970
Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596	90.000000
Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429	59.701493
Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232	194.029851
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284	90.000000
Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084	240.000000
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059	388.059702
Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354	45.000000
Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611	15.000000
Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565	50.000000
Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187	220.000000
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839	164.179104
Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920	320.000000
Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340	280.000000
Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314	220.000000
Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893	26.548673
Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016	35.000000
Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588	95.000000
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295	208.955224
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179	179.104478
Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005	53.333333
Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132	55.000000
Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399	90.000000
Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975	35.000000
Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278	230.000000
Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884	110.000000
Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617	80.000000
Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330	25.000000
Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744	171.641791
Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219	110.000000
Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756	80.000000

…OR overwrite old ones!

cereal$shelf <- as.factor(cereal$shelf)

`group_by()`

(Allison Horst)

`group_by()`

Separate the data into different groups based on a categorical variable.

The data gets grouped, but nothing happens externally.

cereal |> 
  group_by(type)

# A tibble: 77 × 16
# Groups:   type [2]
   name      manuf type  calories protein   fat sodium fiber carbo sugars potass
   <fct>     <fct> <fct>    <int>   <int> <int>  <int> <dbl> <dbl>  <int>  <int>
 1 100% Bran N     cold        70       4     1    130  10     5        6    280
 2 100% Nat… Q     cold       120       3     5     15   2     8        8    135
 3 All-Bran  K     cold        70       4     1    260   9     7        5    320
 4 All-Bran… K     cold        50       4     0    140  14     8        0    330
 5 Almond D… R     cold       110       2     2    200   1    14        8     -1
 6 Apple Ci… G     cold       110       2     2    180   1.5  10.5     10     70
 7 Apple Ja… K     cold       110       2     0    125   1    11       14     30
 8 Basic 4   G     cold       130       3     2    210   2    18        8    100
 9 Bran Chex R     cold        90       2     1    200   4    15        6    125
10 Bran Fla… P     cold        90       3     0    210   5    13        5    190
# ℹ 67 more rows
# ℹ 5 more variables: vitamins <int>, shelf <int>, weight <dbl>, cups <dbl>,
#   rating <dbl>

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954
Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409
Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856
Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025
Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381
Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285
Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500
Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357
Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021
Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645
Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502
Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332
Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279
Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651
Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382
Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564
Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620
Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086
Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758
Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597
Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705
Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549
Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576
Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244
Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404
Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690
Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101
Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172
Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129
Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222
Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241
Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368
Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151
Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111
Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807
Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451
Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092
Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686
Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976
Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335
Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596
Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429
Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284
Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059
Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354
Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611
Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565
Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839
Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920
Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340
Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314
Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893
Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016
Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179
Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005
Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132
Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399
Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975
Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278
Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884
Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617
Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330
Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744
Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219
Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756

`ungroup()`

The ungroup() function will remove the internal grouping in your data.

This is not something that you always need to do, but if you are getting unexpected output downstream from a group_by() statement, try ungrouping your data!

`summarize()`

group_by() is almost always paired with summarize()!

`summarize()`

We can calculate summaries of variables in the data.

cereal |> 
  summarise(mean_fiber = mean(fiber))

  mean_fiber
1   2.151948

Or multiple summaries at the same time.

cereal |> 
summarise(mean_fiber = mean(fiber),
          num_cereals = n(),
          mean_sugar = mean(sugars))

  mean_fiber num_cereals mean_sugar
1   2.151948          77   6.922078

Note

summarize() and summarise() are synonyms!

`summarize()`: Handy Helpers!

mean(), median(), sd(), sum()
min(), max()
n(), n_distinct() – counts the number of (distinct) elements
first(), last(), nth() – extract the first, last, or nth element
across() – apply a function across columns

`group_by() + summarize()`!

group_by a variable (or multiple variables)
summarize a variable (or multiple variables) within the groups

cereal |> 
  group_by(manuf) |> 
  summarise(mean_sugar = mean(sugars))

manuf	mean_sugar
A	3.000000
G	7.954546
K	7.565217
N	1.833333
P	8.777778
Q	5.250000
R	6.125000

`group_by() + mutate()`!

group_by a variable (or multiple variables)
mutate a variable (or multiple variables) within the groups

cereal |> 
  group_by(manuf) |> 
  mutate(mean_sugar = mean(sugars))

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating	mean_sugar
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297	1.833333
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368	5.250000
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551	7.565217
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491	7.565217
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484	6.125000
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954	7.954546
Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409	7.565217
Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856	7.954546
Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025	6.125000
Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381	8.777778
Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285	5.250000
Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500	7.954546
Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357	7.954546
Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021	7.954546
Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645	7.954546
Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502	6.125000
Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332	7.565217
Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279	7.565217
Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651	7.954546
Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877	7.565217
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382	1.833333
Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564	7.565217
Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620	7.954546
Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086	6.125000
Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758	7.565217
Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597	7.565217
Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514	7.565217
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705	8.777778
Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549	7.565217
Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576	8.777778
Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244	8.777778
Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404	7.954546
Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690	8.777778
Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101	8.777778
Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172	8.777778
Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129	5.250000
Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222	7.954546
Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241	8.777778
Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368	7.565217
Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151	7.565217
Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111	7.954546
Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807	5.250000
Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451	7.954546
Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092	3.000000
Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686	6.125000
Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976	6.125000
Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335	7.565217
Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596	7.954546
Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429	7.565217
Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232	7.565217
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284	7.565217
Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084	7.954546
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059	8.777778
Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354	7.565217
Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611	5.250000
Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565	5.250000
Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187	5.250000
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839	5.250000
Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920	7.565217
Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340	7.954546
Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314	7.565217
Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893	6.125000
Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016	7.565217
Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588	1.833333
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295	1.833333
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179	1.833333
Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005	7.565217
Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132	7.565217
Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399	1.833333
Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975	7.954546
Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278	7.954546
Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884	7.954546
Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617	7.954546
Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330	7.954546
Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744	6.125000
Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219	7.954546
Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756	7.954546

The Difference?

group_by() + summarize() collapses the data.

You will only have one row per group remaining.

group_by() + mutate() does not.

You will have the full number of rows remaining.

How do we “group” and “summarize” in base `R`?

You can use the aggregate() function.

cereal |> 
  aggregate(sugars ~ manuf, FUN = mean)

manuf	sugars
A	3.000000
G	7.954546
K	7.565217
N	1.833333
P	8.777778
Q	5.250000
R	6.125000

Glue it all together!

cereal |> 
  filter(type == "cold") |> 
  mutate(potass_per_cup = potass / cups) |> 
  group_by(manuf) |> 
  summarise(mean_potass_per_cup = mean(potass_per_cup))

manuf	mean_potass_per_cup
G	109.1970
K	175.3978
N	284.3089
P	203.8749
Q	93.3511
R	106.8864

Save your changes!

When you manipulate your data, make sure you assign your new dataset to a variable.

cereal_summary <- cereal |> 
  filter(type == "cold") |> 
  mutate(potass_per_cup = potas / cups) |> 
  group_by(manuf) |> 
  summarise(mean_potass_per_cup = mean(potass_per_cup))

Code Formatting

Similar to the + formatting in ggplot, do not continue a line after writing a |>!

Bad Practice
Good Practice

cereal |> group_by(type) |> summarise(mean_fiber = mean(fiber), num_cereals = n(), mean_sugar = mean(sugars))

cereal |> 
  group_by(type) |> 
  summarise(mean_fiber = mean(fiber), 
            num_cereals = n(),
            mean_sugar = mean(sugars))

PA 3: Identify the Mystery College

Today you will use the dplyr package to clean some data and then use that cleaned data to figure out what college Margaret has been accepted to.

Submit the full name of the college Margaret will attend to the Canvas Quiz.

To do…

PA 3: Identify the Mystery College
- Due Wednesday 4/17 at 10:00am

Wednesday, April 17

Today we will…

New Material
- Extend dplyr verbs to have more functionality.
- Think about data ethics.
Lab 3: Teacher Evaluations

Extending `dplyr` verbs

Example Data set – Cereal

library(liver)
data(cereal)
head(cereal)

                       name manuf type calories protein fat sodium fiber carbo
1                 100% Bran     N cold       70       4   1    130  10.0   5.0
2         100% Natural Bran     Q cold      120       3   5     15   2.0   8.0
3                  All-Bran     K cold       70       4   1    260   9.0   7.0
4 All-Bran with Extra Fiber     K cold       50       4   0    140  14.0   8.0
5            Almond Delight     R cold      110       2   2    200   1.0  14.0
6   Apple Cinnamon Cheerios     G cold      110       2   2    180   1.5  10.5
  sugars potass vitamins shelf weight cups   rating
1      6    280       25     3      1 0.33 68.40297
2      8    135        0     3      1 1.00 33.98368
3      5    320       25     3      1 0.33 59.42551
4      0    330       25     3      1 0.50 93.70491
5      8     -1       25     3      1 0.75 34.38484
6     10     70       25     1      1 0.75 29.50954

Count with `count()`

How many cereals does each manuf have in this dataset?

cereal |> 
  group_by(manuf) |> 
  count()

manuf	n
A	1
G	22
K	23
N	6
P	9
Q	8
R	8

Summarize multiple columns with `across()`

For each type of cereal, calculate the mean nutrient levels.

Within the summarize() function, we use the across() function, with three arguments:

.cols – to specify the columns to apply functions to.
.fns – to specify the functions to apply.
.x – as a placeholder for the variables being passed into the function.

We use lambda functions: ~ <FUN_NAME>(.x, <ARGS>)

Summarize multiple columns with `across()`

For each type of cereal, calculate the mean nutrient levels.

cereal |> 
  group_by(type) |> 
  summarise(across(.cols = calories:potass, .fns = ~ mean(.x)))

type	calories	protein	fat	sodium	fiber	carbo	sugars	potass
cold	107.1622	2.486486	1.013513	165.06757	2.189189	14.7027	7.1756757	97.21622
hot	100.0000	4.000000	1.000000	26.66667	1.233333	12.0000	0.6666667	68.00000

cereal |> 
  group_by(type) |> 
  summarise(across(.cols = calories:potass,
                   .fns = ~ mean(.x, trim = 0.1)))

type	calories	protein	fat	sodium	fiber	carbo	sugars	potass
cold	107.6667	2.416667	0.8833333	170.08333	1.800000	14.66667	7.2000000	86.66667
hot	100.0000	4.000000	1.0000000	26.66667	1.233333	12.00000	0.6666667	68.00000

Discretize with `if_else()`

For each cereal, label the potass as “high” or “low”.

One if-else statement:

if_else(<CONDITION>, <TRUE OUTPUT>, <FALSE OUTPUT>)

cereal |> 
  mutate(po_category = if_else(potass <= 100, "low", "high"),
         .after = potass)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	po_category	vitamins	shelf	weight	cups	rating
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	high	25	3	1.00	0.33	68.40297
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	high	0	3	1.00	1.00	33.98368
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	high	25	3	1.00	0.33	59.42551
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	high	25	3	1.00	0.50	93.70491
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	low	25	3	1.00	0.75	34.38484
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	low	25	1	1.00	0.75	29.50954
Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	low	25	2	1.00	1.00	33.17409
Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	low	25	3	1.33	0.75	37.03856
Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	high	25	1	1.00	0.67	49.12025
Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	high	25	3	1.00	0.67	53.31381
Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	low	25	2	1.00	0.75	18.04285
Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	high	25	1	1.00	1.25	50.76500
Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	low	25	2	1.00	0.75	19.82357
Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	high	25	3	1.00	0.50	40.40021
Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	low	25	2	1.00	1.00	22.73645
Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	low	25	1	1.00	1.00	41.44502
Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	low	25	1	1.00	1.00	45.86332
Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	low	25	2	1.00	1.00	35.78279
Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	low	25	2	1.00	1.00	22.39651
Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	high	25	3	1.00	0.50	40.44877
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	low	0	2	1.00	1.00	64.53382
Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	low	25	3	1.00	1.00	46.89564
Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	high	25	3	1.00	0.75	36.17620
Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	low	25	3	1.00	0.75	44.33086
Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	low	25	2	1.00	1.00	32.20758
Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	low	25	1	1.00	0.75	31.43597
Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	low	25	2	1.00	0.80	58.34514
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	high	25	3	1.25	0.67	40.91705
Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	high	25	3	1.33	0.67	41.01549
Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	low	25	2	1.00	0.75	28.02576
Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	low	25	1	1.00	0.88	35.25244
Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	low	25	2	1.00	0.75	23.80404
Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	low	25	3	1.00	0.88	52.07690
Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	low	25	3	1.00	0.25	53.37101
Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	low	25	3	1.00	0.33	45.81172
Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	low	25	2	1.00	1.00	21.87129
Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	low	25	1	1.00	0.75	31.07222
Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	low	25	1	1.00	1.33	28.74241
Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	low	100	3	1.00	1.00	36.52368
Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	low	100	3	1.30	0.75	36.47151
Kix	G	cold	110	2	1	260	0.0	21.0	3	40	low	25	2	1.00	1.50	39.24111
Life	Q	cold	100	4	2	150	2.0	12.0	6	95	low	25	2	1.00	0.67	45.32807
Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	low	25	2	1.00	1.00	26.73451
Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	low	25	2	1.00	1.00	54.85092
Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	high	25	3	1.00	1.00	37.13686
Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	high	25	3	1.00	1.00	34.13976
Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	high	25	3	1.50	0.67	30.31335
Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	low	25	1	1.00	1.00	40.10596
Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	low	25	2	1.00	0.67	29.92429
Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	high	25	3	1.33	0.67	40.69232
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	low	25	3	1.00	1.00	59.64284
Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	high	25	3	1.25	0.50	30.45084
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	high	25	3	1.33	0.67	37.84059
Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	low	100	3	1.00	1.00	41.50354
Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	low	0	3	0.50	1.00	60.75611
Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	low	0	3	0.50	1.00	63.00565
Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	high	25	3	1.00	0.50	49.51187
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	high	0	1	1.00	0.67	50.82839
Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	high	25	2	1.33	0.75	39.25920
Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	high	25	3	1.00	0.50	39.70340
Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	high	25	3	1.00	0.50	55.33314
Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	low	25	1	1.00	1.13	41.99893
Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	low	25	1	1.00	1.00	40.56016
Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	low	0	1	0.83	1.00	68.23588
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	high	0	1	1.00	0.67	74.47295
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	high	0	1	1.00	0.67	72.80179
Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	low	25	2	1.00	0.75	31.23005
Special K	K	cold	110	6	0	230	1.0	16.0	3	55	low	25	1	1.00	1.00	53.13132
Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	low	25	2	1.00	1.00	59.36399
Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	low	100	3	1.00	1.00	38.83975
Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	high	100	3	1.50	1.00	28.59278
Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	high	100	3	1.00	1.00	46.65884
Triples	G	cold	110	2	1	250	0.0	21.0	3	60	low	25	3	1.00	0.75	39.10617
Trix	G	cold	110	1	1	140	0.0	13.0	12	25	low	25	2	1.00	1.00	27.75330
Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	high	25	1	1.00	0.67	49.78744
Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	high	25	1	1.00	1.00	51.59219
Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	low	25	1	1.00	0.75	36.18756

.after – specifies the location of the newly created column

Re-level with `case_when()`

For each manufacturer, change the manuf code to the name.

A series of if-else statements.

cereal |> 
  mutate(manuf = case_when(manuf == "A" ~ "American Home Food Products", 
                           manuf == "G" ~ "General Mills", 
                           manuf == "K" ~ "Kelloggs", 
                           manuf == "N" ~ "Nabisco", 
                           manuf == "P" ~ "Post", 
                           manuf == "Q" ~ "Quaker Oats", 
                           manuf == "R" ~ "Ralston Purina"))

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
100% Bran	Nabisco	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297
100% Natural Bran	Quaker Oats	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368
All-Bran	Kelloggs	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551
All-Bran with Extra Fiber	Kelloggs	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491
Almond Delight	Ralston Purina	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484
Apple Cinnamon Cheerios	General Mills	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954
Apple Jacks	Kelloggs	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409
Basic 4	General Mills	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856
Bran Chex	Ralston Purina	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025
Bran Flakes	Post	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381
Cap'n'Crunch	Quaker Oats	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285
Cheerios	General Mills	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500
Cinnamon Toast Crunch	General Mills	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357
Clusters	General Mills	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021
Cocoa Puffs	General Mills	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645
Corn Chex	Ralston Purina	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502
Corn Flakes	Kelloggs	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332
Corn Pops	Kelloggs	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279
Count Chocula	General Mills	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651
Cracklin' Oat Bran	Kelloggs	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877
Cream of Wheat (Quick)	Nabisco	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382
Crispix	Kelloggs	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564
Crispy Wheat & Raisins	General Mills	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620
Double Chex	Ralston Purina	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086
Froot Loops	Kelloggs	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758
Frosted Flakes	Kelloggs	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597
Frosted Mini-Wheats	Kelloggs	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514
Fruit & Fibre Dates; Walnuts; and Oats	Post	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705
Fruitful Bran	Kelloggs	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549
Fruity Pebbles	Post	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576
Golden Crisp	Post	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244
Golden Grahams	General Mills	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404
Grape Nuts Flakes	Post	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690
Grape-Nuts	Post	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101
Great Grains Pecan	Post	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172
Honey Graham Ohs	Quaker Oats	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129
Honey Nut Cheerios	General Mills	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222
Honey-comb	Post	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241
Just Right Crunchy Nuggets	Kelloggs	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368
Just Right Fruit & Nut	Kelloggs	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151
Kix	General Mills	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111
Life	Quaker Oats	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807
Lucky Charms	General Mills	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451
Maypo	American Home Food Products	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092
Muesli Raisins; Dates; & Almonds	Ralston Purina	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686
Muesli Raisins; Peaches; & Pecans	Ralston Purina	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976
Mueslix Crispy Blend	Kelloggs	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335
Multi-Grain Cheerios	General Mills	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596
Nut&Honey Crunch	Kelloggs	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429
Nutri-Grain Almond-Raisin	Kelloggs	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232
Nutri-grain Wheat	Kelloggs	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284
Oatmeal Raisin Crisp	General Mills	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084
Post Nat. Raisin Bran	Post	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059
Product 19	Kelloggs	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354
Puffed Rice	Quaker Oats	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611
Puffed Wheat	Quaker Oats	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565
Quaker Oat Squares	Quaker Oats	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187
Quaker Oatmeal	Quaker Oats	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839
Raisin Bran	Kelloggs	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920
Raisin Nut Bran	General Mills	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340
Raisin Squares	Kelloggs	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314
Rice Chex	Ralston Purina	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893
Rice Krispies	Kelloggs	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016
Shredded Wheat	Nabisco	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588
Shredded Wheat 'n'Bran	Nabisco	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295
Shredded Wheat spoon size	Nabisco	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179
Smacks	Kelloggs	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005
Special K	Kelloggs	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132
Strawberry Fruit Wheats	Nabisco	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399
Total Corn Flakes	General Mills	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975
Total Raisin Bran	General Mills	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278
Total Whole Grain	General Mills	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884
Triples	General Mills	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617
Trix	General Mills	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330
Wheat Chex	Ralston Purina	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744
Wheaties	General Mills	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219
Wheaties Honey Gold	General Mills	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756

`group_by()` + `slice()`

For each manuf, find the cereal with the most fiber.

cereal |> 
  group_by(manuf) |> 
  slice_max(order_by = fiber)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Maypo	A	hot	100	4	1	0	0.0	16	3	95	25	2	1.00	1.00	54.85092
Total Raisin Bran	G	cold	140	3	1	190	4.0	15	14	230	100	3	1.50	1.00	28.59278
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8	0	330	25	3	1.00	0.50	93.70491
100% Bran	N	cold	70	4	1	130	10.0	5	6	280	25	3	1.00	0.33	68.40297
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11	14	260	25	3	1.33	0.67	37.84059
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1	-1	110	0	1	1.00	0.67	50.82839
Bran Chex	R	cold	90	2	1	200	4.0	15	6	125	25	1	1.00	0.67	49.12025

Multiple Variables in `slice()`

Find the 3 cereals with the highest fiber and potass.

If you are ordering by multiple variables, wrap them in a data.frame!

cereal |> 
  slice_max(order_by = data.frame(fiber, potass),
            n = 3)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
All-Bran with Extra Fiber	K	cold	50	4	0	140	14	8	0	330	25	3	1	0.50	93.70491
100% Bran	N	cold	70	4	1	130	10	5	6	280	25	3	1	0.33	68.40297
All-Bran	K	cold	70	4	1	260	9	7	5	320	25	3	1	0.33	59.42551

Piping into `ggplot()`

Plot the mean protein per cup for each manuf.

cereal |> 
  mutate(manuf = case_when(manuf == "A" ~ "American Home Food Products", 
                           manuf == "G" ~ "General Mills", 
                           manuf == "K" ~ "Kelloggs", 
                           manuf == "N" ~ "Nabisco", 
                           manuf == "P" ~ "Post", 
                           manuf == "Q" ~ "Quaker Oats", 
                           manuf == "R" ~ "Ralston Purina")) |> 
  filter(type == "cold") |> 
  mutate(pro_per_cup = protein / cups) |> 
  group_by(manuf) |> 
  summarise(mean_pro_per_cup = mean(pro_per_cup)) |> 
  ggplot(aes(x = manuf, 
             y = mean_pro_per_cup, 
             shape = manuf)) +
  geom_point(show.legend = FALSE,
             size = 6) +
  labs(x = "Manufacturer",
       subtitle = "Mean Protein per Cup") +
  theme_bw() +
  theme(axis.title.y = element_blank(),
        axis.title.x  = element_text(size = 30),
        plot.subtitle = element_text(size = 32),
        axis.text = element_text(size = 22),
        axis.text.x = element_text(angle = 13)) +
  scale_y_continuous(limits = c(75,225))

Piping into `ggplot()`

Plot the mean protein per cup for each manuf.

cereal |> 
  mutate(manuf = case_when(manuf == "A" ~ "American Home Food Products", 
                           manuf == "G" ~ "General Mills", 
                           manuf == "K" ~ "Kelloggs", 
                           manuf == "N" ~ "Nabisco", 
                           manuf == "P" ~ "Post", 
                           manuf == "Q" ~ "Quaker Oats", 
                           manuf == "R" ~ "Ralston Purina")) |> 
  filter(type == "cold") |> 
  mutate(pro_per_cup = protein / cups) |> 
  group_by(manuf) |> 
  summarise(mean_pro_per_cup = mean(pro_per_cup)) |> 
  ggplot(aes(x = manuf, 
             y = mean_pro_per_cup, 
             shape = manuf)) +
  geom_point(show.legend = FALSE,
             size = 6) +
  labs(x = "Manufacturer",
       subtitle = "Mean Protein per Cup") +
  theme_bw() +
  theme(axis.title.y = element_blank(),
        axis.title.x  = element_text(size = 30),
        plot.subtitle = element_text(size = 32),
        axis.text = element_text(size = 22),
        axis.text.x = element_text(angle = 13)) +
  scale_y_continuous(limits = c(0,6))

Piping into `ggplot()`

Creating a Game Plan

Just like when creating graphics with ggplot, wrangling data with dplyr involves thinking through many steps and writing many layers of code.

To help us think through a wrangling problem, we are going to create a game plan before we start writing code.

This might involve…

a sketch or flowchart.
a list of dplyr verbs and variable names.
annotating the head of the dataframe.

What is the median grams of sugarsper shelf and the number of cereals per shelf, when we drop the missing values (coded as sugars = -1)?

The person with the nearest birthday: explain out loud to your neighbor how you would do this manipulation.

cereal |> 
  select(sugars, shelf) |> 
  filter(sugars != -1) |> 
  group_by(shelf) |> 
  summarise(med_sugars = median(sugars),
            num_shelf = n())

# A tibble: 3 × 3
  shelf med_sugars num_shelf
  <int>      <dbl>     <int>
1     1          3        19
2     2         12        21
3     3          6        36

Thinking about Data Ethics

Data Ethics

1. What do we mean by data ethics?

2. Why do we (as statisticians, data scientists, folks working with data) need to think about data ethics?

Data Ethics

1. What do we mean by data ethics?

The process of evaluating data collection, processing, analysis, and dissemination practices for their adverse impacts on individuals, systems, and society.

2. Why do we (as statisticians, data scientists, folks working with data) need to think about data ethics?

We have a lot of power to declare truth and fact, hiding behind the black box of data science methods.

Data Science Oath

I will not be ashamed to say, “I know not,” nor will I fail to call in my colleagues when the skills of another are needed.
I will respect the privacy of my data subjects, for their data are not disclosed to me that the world may know.
I will remember that my data are not just numbers without meaning or context, but represent real people and situations, and that my work may lead to unintended societal consequences, such as inequality, poverty, and disparities due to algorithmic bias.

ASA Ethical Guidelines

The American Statistical Association’s Ethical Guidelines for Statistical Practice are intended to help statistics practitioners make decisions ethically.
They aim to promote accountability by informing those who rely on statistics of the standards they should expect.

Visit Ethical Guidelines for Statistical Practice and discuss one of the guidelines with your neighbor.

What surprises you? What did you learn?

In what scenario might this come into play?

Institutional Review Board

IRB reviews help to ensure that research participants are protected from research-related risks and treated ethically.
This is a necessary prerequisite for maintaining the public’s trust in research and allowing science to advance for the common good.

Note

Watch a video about IRB to learn more.

Lab 3: Teacher Evaluations

To do…

Lab 3: Teacher Evaluations
- Due Saturday, 4/20 at 11:59pm
Read Chapter 4: Data Joins and Transformations
- Check-in 4.1 + 4.2 due Monday 4/22 at 10:00am

Data Cleaning & Manipulation

Monday, April 15

Comments from Week 2

Citing Your Sources

Example Data set – Cereal

Data Wrangling with dplyr

dplyr

dplyr verbs

The Pipe Operator

The Pipe Operator

The Pipe Operator

The Pipe Operator

Data Comes First!

filter()

filter()

filter()

filter(): Handy Helpers!

filter(): |

filter(): %in%

filter(): Related Functions

How do we “filter” in base R?

arrange()

arrange()

arrange()

arrange(): Descending Order

arrange(): Related Functions

slice_max()

How do we “arrange” in base R?

select()

select()

select()

select(): Reordering

select(): Handy Helpers!

rename()

How do we “select” in base R?

mutate()

mutate()

mutate(): Handy Helpers!

How do we “mutate” in base R?

group_by()

group_by()

ungroup()

summarize()

summarize()

summarize(): Handy Helpers!

group_by() + summarize()!

group_by() + mutate()!

The Difference?

How do we “group” and “summarize” in base R?

Glue it all together!

Save your changes!

Code Formatting

PA 3: Identify the Mystery College

To do…

Wednesday, April 17

Extending dplyr verbs

Example Data set – Cereal

Count with count()

Summarize multiple columns with across()

Summarize multiple columns with across()

Discretize with if_else()

Re-level with case_when()

group_by() + slice()

Multiple Variables in slice()

Piping into ggplot()

Piping into ggplot()

Piping into ggplot()

Creating a Game Plan

Creating a Game Plan

Creating a Game Plan

Thinking about Data Ethics

Data Ethics

Data Ethics

Data Science Oath

ASA Ethical Guidelines

Institutional Review Board

Lab 3: Teacher Evaluations

To do…

Data Wrangling with `dplyr`

`dplyr`

`dplyr` verbs

`filter()`

`filter()`

`filter()`

`filter()`: Handy Helpers!

`filter()`: `|`

`filter()`: `%in%`

`filter()`: Related Functions

How do we “filter” in base `R`?

`arrange()`

`arrange()`

`arrange()`

`arrange()`: Descending Order

`arrange()`: Related Functions

`slice_max()`

How do we “arrange” in base `R`?

`select()`

`select()`

`select()`

`select()`: Reordering

`select()`: Handy Helpers!

`rename()`

How do we “select” in base `R`?

`mutate()`

`mutate()`

`mutate()`: Handy Helpers!

How do we “mutate” in base `R`?

`group_by()`

`group_by()`

`ungroup()`

`summarize()`

`summarize()`

`summarize()`: Handy Helpers!

`group_by() + summarize()`!

`group_by() + mutate()`!

How do we “group” and “summarize” in base `R`?

Extending `dplyr` verbs

Count with `count()`

Summarize multiple columns with `across()`

Summarize multiple columns with `across()`

Discretize with `if_else()`

Re-level with `case_when()`

`group_by()` + `slice()`

Multiple Variables in `slice()`

Piping into `ggplot()`

Piping into `ggplot()`

Piping into `ggplot()`